RF and/or RF identification tag/device having an integrated interposer, and methods for making and using the same

ABSTRACT

A MOS RF surveillance and/or identification tag, and methods for its manufacture and use. The tag generally includes an interposer, an antenna and/or inductor on the interposer, and integrated circuitry on the interposer in a location other than the antenna and/or inductor. The integrated circuitry generally has a lowest layer in physical contact with the interposer surface. The method of manufacture generally includes forming a lowest layer of integrated circuitry on an interposer, forming successive layers of the integrated circuitry on the lowest layer of integrated circuitry, and attaching an electrically conductive functional layer to the interposer. Alternatively, an electrically conductive structure may be formed from a functional layer attached to the interposer. The method of use generally includes causing and/or inducing a current in the present tag sufficient for it to generate, reflect or modulate a detectable electromagnetic signal, detecting the signal, and optionally, processing information conveyed by the detectable electromagnetic signal. The present invention advantageously provides a low cost RFID tag capable of operating at MHz frequencies that can be manufactured in a shorter time period than conventional RFID tags that manufacture all active electrical devices on a conventional wafer.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/617,617, filed Oct. 8, 2004, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of sensors, electronic article surveillance (EAS), radio frequency (RF) and/or RF identification (RFID) tags and devices. More specifically, embodiments of the present invention pertain to EAS, RF and/or RFID structures and methods for their manufacturing and/or production. As a result, the present invention may provide a low-cost process for producing an RFID (or EAS) tag comprising a substrate, an RF front end or subset of an RF front end, memory and logic circuit.

DISCUSSION OF THE BACKGROUND

Remotely powered electronic devices and related systems are known. For example, U.S. Pat. No. 5,099,227, issued to Geiszler et al. and entitled “Proximity Detecting Apparatus,” discloses a remotely powered device which uses electromagnetic coupling to derive power from a remote source, then uses both electromagnetic and electrostatic coupling to transmit stored data to a receiver, often collocated with the remote source. Such remotely powered communication devices are commonly known as radio frequency identification (“RFID”) tags.

RFID tags and associated systems have numerous uses. For example, RFID tags are frequently used for personal identification in automated gate sentry applications, protecting secured buildings or areas. These tags often take the form of access control cards. Information stored on the RFID tag identifies the tag holder seeking access to the secured building or area. Older automated gate sentry applications generally require the person accessing the building to insert or swipe their identification card or tag into or through a reader for the system to read the information from the card or tag. Newer RFID tag systems allow the tag to be read at a short distance using radio frequency data transmission technology, thereby eliminating the need to insert or swipe an identification tag into or through a reader. Most typically, the user simply holds or places the tag near a base station, which is coupled to a security system securing the building or area. The base station transmits an excitation signal to the tag that powers circuitry contained on the tag. The circuitry, in response to the excitation signal, communicates stored information from the tag to the base station, which receives and decodes the information. The information is then processed by the security system to determine if access is appropriate. Also, RFID tags may be written (e.g., programmed and/or deactivated) remotely by an excitation signal, appropriately modulated in a predetermined manner.

Some conventional RFID tags and systems use primarily electromagnetic coupling to remotely power the remote device and couple the remote device with an exciter system and a receiver system. The exciter system generates an electromagnetic excitation signal that powers up the device and causes the device to transmit a signal which may include stored information. The receiver receives the signal produced by the remote device.

On a more basic level, RFID tag circuitry generally performs some or all of the following functions:

-   -   1. Absorption of RF energy from the reader field.     -   2. Conversion of an RF signal into a DC signal that powers the         chip.     -   3. Demodulation of incoming clock, timing and/or command signals         available in the RF signal from the reader.     -   4. State machine decision making and control logic that acts on         incoming or preset instructions.     -   5. Counter- or register-based reading of data in digital form         from a memory array or other source (e.g., the output of a         sensor).     -   6. Storage elements (e.g., memory) that store the ID code or         other information that is to be read out to the reader and/or         used for security authentication (also, e.g., EAS         deactivation-type memory, such as that which is configured to         count a predetermined number of usages [in a transportation         ticket, for instance] and/or to relay information from a sensor         back to the reader).     -   7. Modulation of coded data, timing signals or other commands         back to the tag antenna(e) for transmission to the tag reader.

On the other hand, EAS tag circuitry can eliminate some of these steps and/or functions. For example, logic-based frequency division EAS performs the basic RF energy harvesting to power an internal logic divider that then modulates the antenna(e) of the tag such that a unique subharmonic signal is returned back to the reader (see, e.g., U.K. Pat. Appl. GB 2017454A). This subharmonic signal can easily be differentiated from other noise sources (such as harmonics of the carrier) and produces an effective EAS signal. In some cases, nonlinear effects from semiconductor devices can be used to simplify things even further, such as is disclosed in U.S. Pat. No. 4,670,740. In this latter case, nonlinear effects in a semiconductor diode or varactor lead to subharmonic signals which can be detected by the reader, without the intermediate RF→DC power conversion or logic processing.

Referring to FIG. 1A, conventional RFID tags are formed by a process that can include dicing a wafer 10 manufactured by conventional wafer-based processes into a plurality of die 20, then placing the die 20 either onto an antenna or inductor carrier sheet (which may contain an etched, cut, or printed metal antenna, inductor coil or other conducting feature) or, as shown in FIG. 1B, an interposer strap (or carrier) 40, and the interposer strap 40 may then be attached to an inductor/antenna 52 on a support film 50. This process may include various physical bonding techniques, such as gluing, as well as establishing electrical interconnection(s) via wire bonding, anisotropic conductive epoxy bonding, ultrasonics, bump-bonding or flip-chip approaches. This attachment process often involves the use of heat, time, and/or UV exposure. Since the Si die 20 is usually made as small as possible (<1 mm) to reduce the cost per die, the pad elements for electrical connection on the chip 20 may be relatively small. This means that the placing operation should be of relatively high accuracy for high speed mechanical operation (e.g., placement to within 50 microns of a predetermined position is often required).

As a whole, the process of picking out a separated (sawn) die, moving it to the right place on the antenna(e), inductor, carrier, or interposer to which it is to be bonded, accurately placing it in its appropriate location, and making the physical and electrical interconnections can be a relatively slow and expensive process. In the case of processes that use an intermediate interposer, cost and throughput advantages are achieved by first attaching the die 20 to a web roll of interposer carriers 40, which can be done quickly and sometimes in parallel, as they are generally closely spaced and other novel placement operations such as fluidic self-assembly or pin bed attachment processes can be done more easily. The carriers 40 generally contain an electrical path (e.g., 34 or 36) from the die 20 to relatively larger and/or more widely distributed areas in other locations on the carrier 40 to allow high-throughput, low resolution attachment operations such as crimping or conductive adhesive attach (somewhat functionally similar to a conventional strap, as compared to a pick-and-place and/or wire bonding based process for direct integration of a chip die to an inductor substrate). In some cases, low resolution attach processes suitable for straps could be performed at costs near $0.003 or less, based on commercially available equipment and materials (Mühlbauer TMA 6000 or similar). The carriers 40 are then attached to an inductor (not shown) such that electrical connections are formed at such other locations. This interposer process may also have advantages for flip-chip or bump bonding approaches, where it may be more expensive or disadvantageous to implement the required stubs, bumps or other interconnect elements onto the larger inductor/carrier substrate by conventional means (e.g., wire bonding).

In order to reach the ˜$0.01 RFID tag cost goal for item-level retail applications and other low-cost, high-volume applications, there is a need for a tag structure and process that incorporates (and preferably integrates) a less expensive substrate, a stable and effective antenna, RF front end devices, and high resolution patterned logic circuitry.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to a MOS RF and/or RFID device, sensor or tag having an integrated interposer, and methods for its manufacture and use. The device generally comprises (a) an interposer, (b) an antenna and/or inductor on the interposer; and (c) integrated circuitry on the interposer in a location other than the antenna and/or inductor, the integrated circuitry having a lowest layer in physical contact with a surface of the interposer.

The method of manufacture generally comprises the steps of (1) forming a lowest layer of integrated circuitry on a surface of an interposer; (2) forming successive layers of the integrated circuitry on the lowest layer of integrated circuitry; and (3) attaching an electrically conductive functional layer to the interposer. Alternatively, the method of manufacture may comprise the steps of (1) forming the lowest layer of integrated circuitry on the interposer surface; (2) forming successive layers of integrated circuitry on the lowest layer; and (3) forming an electrically conductive structure from a functional layer attached to the interposer.

The method of use generally comprises the steps of (i) causing or inducing a current in the present device sufficient for the device to radiate, reflect or modulate detectable electromagnetic signals; (ii) detecting the detectable electromagnetic radiation; and optionally, (iii) processing information conveyed by the detectable electromagnetic radiation. Optionally, the method of use may further comprise the step of (iv) transporting or transmitting information from the present device (or sensor) back to a reading device.

One potential approach to producing very low-cost RFID tags may use printing techniques in a web- or sheet-fed process. Printing has potential cost advantages, since it can increase materials utilization (e.g., additive or semi-additive processing), combine deposition and patterning steps, and leverage low capital expenditures and operating costs for equipment. Furthermore, high throughput conventional printing processes can be adapted to flexible substrates (e.g., a plastic sheet or a metal foil), improving tag uses in a number of applications. The materials efficiency and additive processing approaches enables a lower cost per unit area of processed interposers (or die, when used), which enables low cost attach processing and/or integration of passive devices with the active circuitry. Also, mask-less processes such as printing enable facile customization of RF devices, for example where each individual RF device is provided with a unique identification code and/or a unique response time delay with respect to a reader inquiry.

Furthermore, if circuitry can be directly printed on the antenna or inductor structure itself, the attach steps and related costs can be eliminated. This approach diverges from the conventional semiconductor wafer cost reduction approach of reducing die cost by decreasing die size (although this approach may become self-limiting for direct-attached Si RFID tags, as the attach costs increase for smaller die). However, a fully-printed, non-area constrained RFID tag may further benefit from development of certain processes, tools, and/or materials that may not be widely or commercially available. The “integrated interposer” approach outlined herein allows for the combination of printing and low cost per unit area display processing (e.g., 0.35 micron Si die processing costs are presently about $25/in²; conventional display polysilicon processing costs are about $0.50-$0.90/in²; and printing-based processing is expected to cost<<$0.50/in²).

By using an interposer-based process, some or all conventional thin film display and photovoltaic materials processing is possible. Photovoltaic materials processing includes well-developed roll-to-roll manufacturing processes for inorganic semiconductors, dielectrics and other films on foils, sheets and/or other flexible substrates. For single films, the cost for such processing can be in the range of about $0.01/in² or less. Thus, the cost for such processing is not prohibitive for a relatively small interposer (25 mm² or so), whereas it is expected to be prohibitive if the entire inductor or antennae substrate must be processed (i.e., an area>>100 mm²). The cost savings can be greater than the low resolution interposer attach costs ($0.003), and such processing provides an effective way to make RFID tags with display and photovoltaics type process equipment by itself (or alternatively, in combination with printing steps that may enable a full manufacturing process without waiting for a full tool and materials set to be developed for printed RFID tags). Ultimately, however, such processing includes spool-based and/or roll-to-roll printing processes, which should drive the manufacturing costs even lower due to the lower capital equipment costs, the high throughput (several hundreds of m²/hr), the increased efficiency in materials usage, and/or the decreased number of processing steps.

The present invention advantageously provides a low cost RF and/or RFID tag capable of standard applications and operations using conventional RF, RFID and/or electronic article surveillance (EAS) equipment and systems. By reducing the number of expensive and/or low throughput attachment steps, as well as reducing the cost of fabricating the active electronics, a low cost tag may be produced by directly printing or otherwise forming the circuitry on an interposer that is then relatively cheaply attached at relatively low accuracy to an inductor/carrier. These and other advantages of the present invention will become readily apparent from the detailed description of preferred embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C show steps in a conventional process for manufacturing RFID tags involving attachment of a conventional semiconductor die on an interposer.

FIGS. 2A-2C show key steps in an exemplary process for manufacturing the present RFID tag/device having an integrated interposer.

FIGS. 3A-3H show key steps in exemplary processes for making integrated circuitry on an interposer substrate for the present RFID tag/device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be readily apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present invention.

For the sake of convenience and simplicity, the terms “coupled to,” “connected to,” and “in communication with” mean direct or indirect coupling, connection or communication unless the context indicates otherwise. These terms are generally used interchangeably herein, but are generally given their art-recognized meanings. Also, for convenience and simplicity, the terms “RF,” “RFID,” and “identification” may be used interchangeably with respect to intended uses and/or functions of a device and/or tag, and the term “tag” or “device” may be used herein to refer to any RF and/or RFID sensor, tag and/or device. Also, the term “integrated circuitry” refers to a unitary structure comprising a plurality of electrically active devices formed from a plurality of conductor, semiconductor and insulator thin films, but generally does not include discrete, mechanically attached components (such as die, wire bonds and leads, the interposer, or an antenna and/or inductor component), or materials having primarily an adhesive function. In addition, the terms “item,” “object” and “article” are used interchangeably, and wherever one such term is used, it also encompasses the other terms. In the present disclosure, a “major surface” of a structure or feature is a surface defined at least in part by the largest axis of the structure or feature (e.g., if the structure is round and has a radius greater than its thickness, the radial surface[s] is/are the major surface of the structure).

The present invention concerns a RF sensor, RF surveillance and/or RF identification device, comprising (a) an interposer, (b) an antenna and/or inductor on the interposer; and (c) integrated circuitry on a surface of the interposer in a location other than the antenna and/or inductor, the integrated circuitry having a lowest layer in physical contact with the surface of the interposer. In various embodiments, the integrated circuitry comprises thin film transistors, diodes, optional capacitors and/or resistors, and metallization interconnecting such circuit elements. In other embodiments, at least one layer of the integrated circuitry comprises a printed or laser patterned layer.

In a further aspect, the present invention concerns a method of manufacturing a sensor, surveillance and/or identification device, generally comprising the steps of (1) forming a lowest layer of integrated circuitry on a surface of an interposer; (2) forming successive layers of the integrated circuitry on the lowest layer of integrated circuitry; and (3) attaching an electrically conductive functional layer to the interposer. Alternatively, the method of manufacture may comprise the steps of (1) forming the lowest layer of integrated circuitry on the interposer surface; (2) forming successive layers of integrated circuitry on the lowest layer; and (3) forming an electrically conductive structure from a functional layer attached to the interposer. In various embodiments, one or more layers of the integrated circuitry are formed by printing or laser patterning the layer of material. In one implementation, forming the lowest layer of integrated circuitry comprises printing or laser patterning the lowest layer.

In an even further aspect, the present invention concerns a method of detecting an item or object, generally comprising the steps of (A) causing or inducing a current in the present surveillance and/or identification device affixed to or associated with the item or object sufficient for the device to radiate, reflect or modulate detectable electromagnetic signals; (B) detecting the detectable electromagnetic radiation; and optionally, (C) processing information conveyed by the detectable electromagnetic radiation. Optionally, the method may further comprise the step of transporting or transmitting information from the present device (or sensor) back to a reading device. The invention, in its various aspects, will be explained in greater detail below with regard to exemplary embodiments.

Exemplary MOS RFID Tags/Devices

One aspect of the invention relates to an RF identification device, comprising (a) an interposer; (b) an antenna and/or inductor on the interposer; and (c) integrated circuitry on the interposer in a location other than the antenna and/or inductor, the integrated circuitry having a lowest layer in physical contact with the surface of the interposer. As a result, the present invention provides a low-cost RFID (or EAS) tag (which may also include sensors, the signal modulation activities of which generally change as a result of certain external changes in the environment [e.g., temperature, conductivity of the structure or surface to which the sensor is attached, etc.], and active RFID devices; e.g., tags with a battery on board) comprising a substrate (e.g., an interposer), an inductor/antenna, and an RF front end (or subset of an RF front end and logic circuit) fully capable of operating in accordance with modern RFID standards.

It has been shown that printed electronics based on inorganic materials (e.g., laser printed nanocrystals) can be formed on certain flexible substrates, such as high temperature polyimides or metal foils, if a suitable thermal isolation/barrier layer is inserted between the substrate (e.g., the metal foil) and subsequent layers that will be laser processed. Thus, the present invention makes advantageous use of such materials as a substrate or interposer in a flexible, (at least partially) printed EAS, RF or RFID tag or device.

The interposer generally has a size that can be cost-effectively processed using conventional thin film processes and/or emerging or state-of-the-art printing processes, to produce low-cost RF circuits. Integrated circuitry can be formed on a flexible interposer substrate such as polyimide, glass/polymer laminate, high temperature polymer, or metal foil, all of which may further include one or more barrier coats. Such interposer substrates are generally substantially less expensive than a conventional Si die of similar size. (However, a conventional RFID interposer typically has a size on the order of 1 cm² in area, as compared to a conventional Si RFID die, which might be about 0.01 cm² or less in area.)

It may be advantageous to use as the interposer substrate an anodized Al, Al/Cu, stainless steel or similar metal foil as interconnect, electrodes and dielectric for large storage or IC resonance capacitors, inductors and/or as an electrode for a diode, MOS-device or FET, or as a WORM/OTP, deactivation or other memory storage element. Examples of such substrates can be found in U.S. patent application Ser. Nos. 10/885,283 and 11/104,375. As a result, in many embodiments, the antenna and/or inductor will be on a first surface of the interposer, and the integrated circuitry will be on a second surface of the interposer opposite the first surface.

Thus, the invention may relate to an identification device, comprising (a) an interposer, (b) an antenna and/or inductor on a first surface of the interposer; and (c) integrated circuitry on a second surface of the interposer opposite the first surface, the integrated circuitry having a lowest layer in physical (and, in some embodiments, electrical) contact with the second surface of the interposer. In one embodiment, the integrated circuitry comprises at least one printed layer. The printed layer(s) may comprise a semiconductor layer, an interlayer dielectric layer, a metal interconnect layer, and/or a gate metal layer.

In general, the integrated circuitry may comprise a gate metal layer; one or more semiconductor layers (e.g., a transistor channel layer, a source/drain terminal layer, and/or one or more lightly- or heavily-doped diode layers); a gate insulator layer between the gate metal layer and a semiconductor layer; one or more capacitor electrodes (each of which is generally capacitively coupled to another capacitor electrode, which may also be part of the integrated circuitry or which may be integrated with or part of the interposer or antenna/inductor layer); a plurality of metal conductors in electrical communication with the gate metal layer, the source and drain terminals, and/or an uppermost diode layer and/or capacitor electrode; and/or an interlayer dielectric between the metal conductors and the semiconductor layer. The integrated circuitry may further comprise one or more resistors, which may comprise a metal and/or lightly or heavily doped polysilicon. In one embodiment, the integrated circuitry comprises a gate metal layer, a plurality of semiconductor layers (a transistor channel layer in contact with a source/drain terminal layer), a gate insulator layer between the gate metal layer and the transistor channel layer, and a plurality of metal conductors in electrical communication with the gate metal layer and the source and drain terminals. Exemplary layers of integrated circuitry are described in greater detail below, with regard to an exemplary method of making a MOS RFID tag/device.

The interposer may comprise a flexible material that may be adapted to withstand relatively high-temperature processing (e.g., a temperature of 300° C., 350° C., 400° C., 450° C. or more, up to a temperature of 500° C., 600° C., or 1000° C., generally without significant deterioration or decrease in its mechanical and/or electrical properties). For example, the interposer may comprise a thin (50-200 micron) glass sheet or “slip,” a glass/polymer laminate, a high temperature polymer (e.g., a polyimide, a polyethersulfone, polyethylene naphthalate [PEN], polyether ether ketone [PEEK], etc.), or a metal foil such as aluminum or stainless steel. Exemplary thicknesses depend on the material used, but in general, range from about 25 μm to about 200 μm (e.g., from about 50 μm to about 100 μm).

The antenna and/or inductor may comprise the antenna, the inductor, or both, and may further comprise a capacitor electrode coupled thereto or integrated therewith (see, e.g., U.S. patent application Ser. Nos. 10/885,283 and 11/104,375, filed on Jul. 6, 2004 and Apr. 11, 2005, respectively, the relevant portions of which are incorporated herein by reference). Generally, the antenna and/or inductor comprises a metal. In one embodiment, the metal may be one commercially available as a foil (e.g., aluminum, stainless steel, copper, or an alloy thereof). In such cases (and where antenna and/or inductor components made from the metal foil, on the one hand, and the integrated circuitry on the other hand are on opposite sides of the interposer), the method of making a RFID and/or EAS device (see the following section) may further comprise the step of removing from the metal foil one or more portions of the metal located under (or opposite) electrically active integrated circuitry (e.g., transistors and diodes, but not necessarily capacitors using a portion of the metal foil as an electrode or plate).

In an embodiment comprising both an antenna and an inductor, the inductor may function as a tuning inductor (see, e.g., U.S. patent application Ser. No. 11/104,375. As a result, the metal forming the antenna and inductor may not be continuous (i.e., it may contain an electrical disconnection).

The present device may also further comprise a support and/or backing layer (not shown) on a surface of the inductor opposite the dielectric film. The support and/or backing layer are conventional, and are well known in the EAS and RFID arts (see, e.g., U.S. Pat. Appl. Publication No. 2002/0163434 and U.S. Pat. Nos. 5,841,350, 5,608,379 and 4,063,229, the relevant portions of each of which are incorporated herein by reference). Generally, such support and/or backing layers provide (1) an adhesive surface for subsequent attachment or placement of the tag/device onto an article to be tracked or monitored, and/or (2) some mechanical support for the tag/device. For example, the present device may be affixed to the back of an identification label or price tag, and an adhesive coated or placed on the surface of the device opposite the identification label or price tag (optionally covered by a conventional release sheet until the label or tag is ready for use), to form a label or tag suitable for use in a conventional RFID system.

Exemplary Method(s) for Making a MOS RFID Tag/Device

In one aspect, the present invention concerns a method for making an identification device, comprising the steps of: (1) forming a lowest layer of integrated circuitry on an interposer; (2) forming successive layers of the integrated circuitry on the lowest layer of integrated circuitry; and (3) attaching an electrically conductive functional layer to the interposer, generally in a location other than the integrated circuitry. Alternatively, the method of manufacture may comprise the steps of (1) forming the lowest layer of integrated circuitry on the interposer surface; (2) forming successive layers of integrated circuitry on the lowest layer; and (3) forming an electrically conductive structure from the interposer (e.g., when the interposer comprises an electrically conductive material, such as a metal foil) or a functional layer attached to the interposer (e.g., when the interposer comprises a laminate of an electrically conductive material and an electrically inactive material, such as a metal foil having an anodized oxide film formed or grown thereon). Thus, the present method provides a cost-effective method for manufacturing RFID devices.

A first exemplary method for manufacturing the present RFID device is described below with reference to FIGS. 2A-2C. FIG. 2A shows tag precursor 100, comprising interposer 132, having thereon pads 134 and 136 and integrated circuitry 110. Generally, integrated circuitry 110 is formed on a first major surface of interposer 132. The integrated circuitry 110 can be realized as a printed inorganic circuit, largely using the techniques described in U.S. patent application Ser. Nos. 10/885,283 and 11/104,375, filed on Jul. 6, 2004 and Apr. 11, 2005, respectively, the relevant portions of which are incorporated herein by reference. Exemplary steps in forming “bottom gate” devices using this approach are described below and are depicted in partial cross-section in FIGS. 3A-3H.

Thereafter, pads 134 and 136 are formed on the same surface of interposer 132 as integrated circuitry 110, similar to the process for forming pads 34 and 36 in FIG. 1A. However, in the exemplary process of FIG. 2A, there are generally holes or vias present in the uppermost dielectric layer of integrated circuitry 110 (sometimes known as the passivation layer) to enable electrical communication with circuit elements therein (generally, upper layer metallization or interconnects; see, e.g., FIGS. 3G-3H and the discussion thereof below). Pads 134 and 136 provide essentially the same function as pads 34 and 36 in FIG. 1A.

Next, holes or vias may be formed in the major surface of interposer 132 opposite that on which pads 134 and 136 and integrated circuitry 110 have been formed. Generally, and referring now to FIG. 2A, there is one hole or via through interposer 132 exposing a surface of pads 134 and 136 and enabling electrical connection to a terminal of antenna/inductor 152. Generally, each hole/via is in a location and has dimensions enabling facile contact between one terminal of antenna/inductor 152 and the corresponding pad, using a relatively high-throughput, low resolution attachment operation (as compared to a pick-and-place operation or wire bonding process for integration of a die 20 to an inductor substrate 40; see FIG. 1B). Referring back to FIGS. 2B-2C, inductor and/or antenna 152 (which may be affixed to or positioned on an applicator sheet 150) is then attached or affixed to interposer 132 such that electrical connections are formed between pads 134 and 136 and terminals of antenna/inductor 152 at locations corresponding to the holes or vias in interposer 132. A short annealing step (which may further comprise applying a small pressure to the opposed major surfaces of integrated interposer 132 and applicator sheet 150) may secure the inductor and/or antenna 152 relatively reliably to the integrated interposer 132.

The process described here can result in a lower overall tag cost by reducing the number of expensive/low throughput attachment steps, as well as reducing the cost of fabricating the active electronics. A low cost tag may be produced by directly printing or otherwise forming the circuitry on an interposer that is then relatively cheaply attached at relatively low accuracy to an inductor/carrier. This may be advantageous where the processing of the circuitry may be performed on a flexible substrate such as polyimide, glass/polymer laminate, high temperature polymer, or metal, all of which may further include one or more barrier coats.

The interposer is generally of a size that enables cost-effective manufacturing using conventional thin film processes, as well as conventional and/or state-of-the-art printing processes, to produce low-cost RF circuits. These processes include sputtering, evaporation, LPCVD, PECVD, bath etching, dry etching, direct laser printing of device elements, ink jet printing of any element or layer, spray coating, blade coating, extrusion coating, photolithography, printed etch mask lithography of any layer (such as laser or inkjet), offset printing, gravure printing, embossing, contact printing, screen printing, combinations thereof, and/or other techniques. Nearly any layer of material in the integrated circuitry of the present invention can be made by essentially any of these techniques. In particular, the present invention enables low-cost manufacturing of RFID and/or EAS tags by low-cost process technologies, such as printing or a combination of printing and conventional display (e.g., flat panel display) processing. In the latter case, use of the interposer as a substrate for manufacturing integrated circuitry enables a decrease in the effective area onto which active materials may be blanket-deposited (e.g., by CVD) and/or processed by equipment/processes conventionally used to make the integrated circuitry. Thus, the present method may further comprise the step of forming one or more second layers of the integrated circuitry by conventional display processing, for example.

As will become apparent from the following description, in the present invention, the antenna and/or inductor can be formed on the same side or on opposite sides of the interposer. Also, equipment that processes continuous roll- or spool web-based substrates can be used to make the present integrated circuitry on the interposer (as well as to attach the antenna/inductor structure, in those embodiments in which the antenna and/or inductor are attached to the interposer after making the integrated circuitry).

Exemplary Method(s) for Making Integrated Circuitry

Generally, integrated circuitry is formed directly on a first major surface of interposer 132. For “top gate” type devices with integrated capacitors and diodes, the integrated circuitry 110 can be realized as a (partially) printed, substantially inorganic circuit, using the techniques described in U.S. patent application Ser. Nos. 11/084,448 and 11/203,563, filed on Mar. 18, 2005, and Aug. 11, 2005, and U.S. Provisional Patent Application Nos. 60/663,296 and 60/697,599, filed on Mar. 18, 2005 and Jul. 8, 2005, respectively, the relevant portions of which are incorporated herein by reference.

Exemplary steps in forming “bottom gate” devices are described below and are depicted in partial cross-section in FIGS. 3A-3H. Many of the techniques described below (although not necessarily used to make bottom gate devices) are described in U.S. patent application Ser. Nos. 11/084,448, 60/663,296 and 60/697,599, and may also be disclosed in U.S. patent application Ser. Nos. 10/885,283, 60/592,596 and 11/104,375, filed on Jul. 6, 2004, Jul. 31, 2004, and Apr. 11, 2005, respectively, the relevant portions of which are incorporated herein by reference.

Prepare Interposer Substrate

Referring now to FIG. 3A, the interposer substrate 210 may comprise any flexible or inflexible, electrically active or insulative substrate capable of (i) providing physical support for the integrated circuitry formed thereon during formation thereof and for the RF transmitter/receiver components attached thereto during attachment thereof, (ii) having integrated circuitry formed (preferably printed) thereon, and (iii) enabling electrical connections to be formed therethrough (i.e., so that signals can be transmitted between integrated circuitry formed on one major surface of the interposer and the RF receiver/transmitter components attached to the opposite major surface of the interposer). The interposer 210 may thus comprise a metal foil (preferably, with a dielectric film [which may be anodized] thereon), polyimide, thin glass, or inorganic/organic laminate substrate.

Preferably, the interposer substrate 210 is conventionally cleaned and coated with a barrier material 220 (such as silicon dioxide or aluminum oxide) before further processing. The coating step may comprise oxidation and/or anodization of a surface material of the interposer substrate (e.g., a metal foil), deposition of spin-on or fluid coated barrier films (Honeywell AcuGlass series or others), sputtering, CVD, or spray coating a barrier material onto the interposer substrate, or a combination of any of these processes. As shown in FIG. 3A, the barrier material 220 a-b coats at least two major surfaces of the interposer 210. Optionally, the surface of at least one barrier material layer (e.g., 220 a) may be treated (e.g., roughened, activated, etc.) and/or cleaned prior to the next step. To the extent the interposer comprises a metal sheet or foil, the metal foil may be etched and/or cut as described in U.S. patent application Ser. Nos. 10/885,283 and 11/104,375, filed on Jul. 6, 2004 and Apr. 11, 2005, respectively, and/or in U.S. Provisional Patent Application No. 60/697,599, filed on Jul. 8, 2005 (the relevant portions of which are incorporated herein by reference), to isolate the contact pads for the antenna.

Gate and Gate Layer Interconnect Formation

Referring now to FIG. 3B, a gate metal layer 230 may be conventionally sputtered onto barrier material layer 220 a. The gate metal layer 230 may comprise any metal conventionally used in integrated circuits and/or printed circuitry, such as aluminum, titanium, tantalum, chromium, molybdenum, tungsten, iron, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, etc., or alloy thereof, such as aluminum-titanium, aluminum-copper, aluminum-silicon, molybdenum-tungsten, titanium-tungsten, etc., or electrically active (e.g., conductive) compound thereof, such as titanium nitride, titanium silicide, tantalum nitride, tantalum silicide, molybdenum nitride, molybdenum silicide, tungsten nitride, tungsten silicide, cobalt silicide, etc. Gate metal layer 230 may have a conventional thickness (e.g., of from 50 nm to 5000 nm, preferably from 80 nm to 3000 nm, more preferably from 100 nm to 2500 nm, or any range of thicknesses therein).

Thereafter a resist may be deposited thereon. The resist may comprise a conventional photoresist or a thermal resist, and may be conventionally deposited or formed on gate metal layer 230 (e.g., spin coating or ink jetting). Conventional photolithography or print/pattern lithography by laser irradiation may be performed (e.g., selectively irradiating portions of the resist, then developing the resist [selectively removing irradiated or non-irradiated portions of the resist, depending on whether the resist is positive or negative] with a conventional developer; see, e.g., U.S. Provisional Patent Application No. 60/663,296 and/or U.S. patent application Ser. No. 11/203,563, filed on Mar. 18, 2005 and Aug. 11, 2005, respectively, the relevant portions of which are incorporated herein by reference) to leave a patterned resist 235 that defines the gates, as shown in FIG. 3B, and gate-level interconnects (not shown, but which may take the form of a conventional “landing pad” located outside the cell or active area of a transistor or other circuit component formed from gate metal layer 230). The exposed gate metal 230 is then etched, and the patterned resist 235 stripped, to form gates (e.g., 232 and 234 as shown in FIG. 3C) and gate-level interconnects. Alternatively, the gate layer 230 may be deposited and patterned by printing (e.g., inkjetting) of a metal precursor ink and subsequent curing, and/or laser patterning of a metal precursor layer (which may include both direct conversion [e.g., laser-induced direct conversion to metal] and indirect conversion [e.g., laser-induced crosslinking of metal-containing species and subsequent annealing to form a conductive metal film]).

Form Gate Dielectric

Referring now to FIG. 3D, a gate dielectric layer 240 (comprising, e.g., a nitride and/or oxide of silicon, aluminum, etc.) is formed over the gates and gate-level interconnects 232 and 234 by sputtering, CVD or other blanket deposition process. Gate dielectric layer 240 may have a thickness of from 10 nm to 100 nm, preferably from 10 nm to 50 nm, more preferably from 10 nm to 40 nm, or any range of values therein.

Alternatively, gate dielectric layer 240 may be printed (e.g., by ink jetting or other printing process described in U.S. patent application Ser. Nos. 10/885,283 and/or 11/104,375) over the gates and gate-level interconnects 232 and 234. Appropriate film properties and/or qualities (e.g., thickness, density, dielectric constant, etc.) may be provided by printing and subsequently processing a plurality of layers. Such subsequent processing may comprise oxidizing a printed dielectric precursor material (such as nanoparticles of silicon and/or aluminum), densifying the dielectric material, doping the dielectric material, etc.

In a further alternative, a gate dielectric layer may be formed from gate-level metal structures 232 and/or 234 by direct, conventional thermal or electrochemical (e.g., anodic) oxidation of gate metal 232 and/or 234. One or more of the gate-level metal structures may be conventionally masked (e.g., with a photo- or laser-patternable resist) if a dielectric film is not desired thereon.

Form Semiconductor Layer(s)

Thereafter, as shown in FIG. 3D, a semiconductor layer 250 (which may comprise intrinsic or lightly doped Si) may be sputtered, coated or otherwise blanket deposited (e.g., by CVD) over the gate dielectric layer 240. Semiconductor layer 250 may have a thickness of from 80 nm to 2000 nm, preferably from 100 nm to 1500 nm, more preferably from 150 nm to 1000 nm, or any range of values therein. Semiconductor layer 250, which may be patterned by conventional photolithography or laser patterning (see, e.g., U.S. Provisional Patent Application No. 60/663,296 and/or U.S. patent application Ser. No. 11/203,563, filed on Mar. 18, 2005 and Aug. 11, 2005, respectively, the relevant portions of which are incorporated herein by reference), may function generally as a transistor channel.

Optionally, a contact layer may be formed on semiconductor (channel) layer 250 by conventional masking and ion implantation, or by sputtering, coating or otherwise blanket depositing (e.g., by CVD) a heavily doped Si (source/drain) contact layer onto semiconductor layer 250. Then, if the source/drain contact layer is blanket deposited, source and drain contact structures 252 a and 252 b may be formed by conventional planarization (e.g., polishing [chemical-mechanical polishing], or deposition of a thermally planarizable material such as a resist and non-selective etch back), and silicon islands may be formed by conventional photolithography, laser irradiation of thermal resists or printed (e.g., ink jetted) resist lithography patterning, followed by dry or wet etching and resist stripping. Portion(s) 255 of the heavily doped Si layer over the gate may be either not formed (e.g., not printed) or removed (e.g., by photolithography and etching, or by forming layer 252 as an amorphous layer, then not laser irradiating [e.g., crystallizing] that portion and removing the non-irradiated portion by etching it selectively to the crystallized silicon) prior to subsequent processing.

Alternatively, and also as shown in FIG. 3E, semiconductor layer 250 and heavily doped Si contact layer 252 a-b may be printed from a semiconductor (e.g., doped or undoped silane) ink in locations corresponding to the silicon islands; see, e.g., U.S. patent application Ser. Nos. 10/789,317, 10/950,373, 10/949,013 and 10/956,714, and U.S. Provisional Patent Application No. 60/617,562), filed on Feb. 27, 2004, Sep. 24, 2004, Sep. 24, 2004, Oct. 1, 2004, and Oct. 8, 2004, respectively, the relevant portions of which are incorporated herein by reference. Generally, semiconductor layer 250 is printed and subsequently processed before heavily doped Si contact layer 252 a-b (i.e., without the portion 255 above the gate) is printed thereon. After printing, the ink is dried, cured and/or annealed to change its morphology (e.g., at least partially crystallize the dried ink). Annealing or laser irradiation may also activate some or all of the dopant therein. Printing not only increases throughput by avoiding resist deposition and removal steps, but also enables direct formation of discrete source and drain contact layers 252 a and 252 b.

Form Interlayer Dielectric and Vias

Formation of the interlayer dielectric and vias from the semiconductor and gate layers is largely conventional. For example, as shown in FIG. 3F, a relatively thick dielectric layer 260 may be deposited onto semiconductor layer 250 (and, if present, contact layer 252), then vias 262 may be formed by conventional photolithography, laser irradiation of thermal resists or printed resist lithography patterning, followed by a conventional dielectric etch. Alternatively, a patterned dielectric layer 260 (e.g., with vias 262 formed therein) may be printed onto semiconductor layer 250 (e.g., by inkjetting, as explained above with regard to the gate dielectric layer 240). Interlayer dielectric 260 may have a thickness, for example, of at least 0.5 μm, and preferably from 1 to 25 μm, 2 to 10 μm, or any range of values therein.

Form Source/Drain (S/D) and Interlayer Interconnects

If heavily doped semiconductor layer 252 a-b has not been formed (see, e.g., FIG. 3E), S/D layer 270 may be sputtered, coated or otherwise blanket deposited onto interlayer dielectric 260 and into vias 262. Typically, S/D layer 270 comprises a heavily doped semiconductor material, similar to heavily doped semiconductor layer 252 a-b. S/D layer 270 may have a thickness, for example, of from 20 nm to 1000 nm, preferably from 40 nm to 500 nm, more preferably from 50 nm to 100 nm, or any range of values therein.

Referring now to FIG. 3G, interconnect metal 280 may be sputtered, coated or otherwise blanket deposited onto S/D layer 270 (including into vias 262). Interconnect metal 280 generally comprises a metal, alloy or electrically active compound, similar to gate metal 230, and may have a thickness, for example, of from 0.5 to 10 μm, preferably from 0.75 to 8 μm, and more preferably from 1 to 5 μm, or any range of values therein. Since interconnect metal 280 may contact a silicon-containing layer, interconnect metal 280 may further comprise a lower silicon barrier layer (e.g., a metal nitride, such as TiN).

Conventional photolithography, laser irradiation of a thermal resist or ink jet resist patterning of the blanket-deposited S/D and interlayer interconnect layers defines the S/D regions and interlayer interconnects, and conventional metal (and semiconductor) etching forms the actual interconnects. Similar connections may be formed to predetermined locations along the gate metal, but preferably in a location other than (e.g., outside of) the silicon islands 255 (see, e.g., FIG. 3E).

Alternatively, and as shown in FIG. 3H, S/D structures 272-278 may be printed from a semiconductor (e.g., doped or undoped silane) ink in locations corresponding to vias 262 (see, e.g., U.S. patent application Ser. Nos. 10/885,283 and/or 11/104,375). If an undoped ink is used, the process for forming S/D structures 272-278 may further comprise a doping step (e.g., comprising conventional ion implantation or ion shower doping). Thereafter, interconnect metal structures 280 may be formed as described above, with the addition of lower adhesive and/or silicon barrier layers, if desired.

After formation of the integrated circuitry is substantially complete, the present method may further comprise the step of passivating the integrated circuitry and/or the device (e.g., forming a passivation or dielectric layer over the integrated circuitry and, to the extent they may be exposed, portions of the interposer or substrate). The passivation layer generally inhibits or prevents the ingress of water, oxygen, and/or other species that could cause the degradation or failure of the integrated circuitry or device, and may add some mechanical support to the device, particularly during further processing. The passivation layer may be formed by conventionally coating the upper surface of the integrated circuitry and/or device with one or more inorganic barrier layers such as a polysiloxane; a nitride, oxide and/or oxynitride of silicon and/or aluminum; and/or one or more organic barrier layers such as parylene, a fluorinated organic polymer, or other barrier material. Alternatively, the passivation layer may further comprise an underlying dielectric layer, which may comprise a material having lower stress than the overlying passivation layer. For example, the dielectric layer may comprise an oxide, such as SiO₂ (e.g., CVD TEOS), USG, FSG, BPSG, etc., and the passivation layer may comprise silicon nitride or a silicon oxynitride. Also, the passivation layer may have a thickness slightly greater than that of the dielectric layer.

At this point in the processing (or at any point where a further material providing some physical or mechanical support to the integrated circuitry or device is added), the mechanical or physical support function of the interposer is no longer necessary. As a result, parts of the interposer supporting the integrated circuitry can be removed entirely (e.g., in the case where the interposer is generally electrically insulating) or in part (e.g., in the case where the interposer is electrically conducting, such as a metal foil, in which case the remaining parts of the interposer may form an antenna, one or more inductors, and/or wire electrically connecting the antenna and/or inductor to a via or contact through the [remaining] interposer to the integrated circuitry or a separate wire thereto). In such a case, the interposer in the final device, tag or sensor may be a dielectric film or other insulator formed on the same surface of the metal foil on which the integrated circuitry is formed.

Hybrid Integrated Circuitry

Alternatively, the tag precursor (e.g., interposer 132 in FIG. 2A having integrated circuitry 110 and pads 132-134 thereon) could take a “hybrid” form. For example, it may be advantageous to combine a printed, inorganic semiconductor- and/or conductor-based RF “front end” in conjunction with a relatively inexpensive, easily fabricated, relatively high functionality organic or conventional Si chip based (digital) logic and/or memory circuit. The term “RF front end” refers to the inductors, capacitors, diodes, and FETs that operate at or near the carrier frequency and/or that modulate that frequency, and is shown by the “IC” area 110 in FIGS. 2A-2C. These elements (and circuit blocks comprising or consisting essentially of such elements) are generally analog in nature (e.g., they function and/or operate in an analog or continuous manner), and may require higher performance devices than the relatively slow, digital logic circuit.

This “hybrid” form may be a particularly advantageous combination in the case of organic circuitry, which may possess certain advantages in terms of cost of materials and/or manufacture. Organic circuitry may be suitable for the controller, logic and/or memory sections of the circuit, which often operate at frequencies significantly lower than the RF frequency (e.g., at 1 MHz or lower). However, organic FET circuitry may not be able to operate effectively at the carrier frequency (e.g., about 13.56 MHz or higher). For example, the design and manufacture of diodes having the desired rectification, leakage and breakdown characteristics based on organic materials have some documented challenges. It may also be difficult to realize effective organic modulation FETs or organic clock-related FETs that operate at the carrier RF frequency. In this case, a hybrid circuit comprising an RF front end as disclosed herein and that is fabricated from high performance printed inorganics, and an organic logic and/or memory circuit which could be fabricated directly on to the RF front end (which would act as the underlying substrate or carrier), may be manufacturable.

As a result, the present invention relates to a method of making an identification device or tag, comprising (1) forming a lowest layer of integrated circuitry on a first surface of an interposer; (2) forming successive layers of the integrated circuitry on the lowest layer of integrated circuitry; and (3) attaching an electrically conductive functional layer to a second surface of the interposer opposite the first surface. The present invention therefore enables a low-cost process for producing an RFID (or EAS) tag comprising a substrate, an RF front end or subset of an RF front end and logic circuit.

An Exemplary Method of Reading the Present RFID Tags

The present invention further relates to method of detecting an item or object in a detection zone comprising the steps of: (a) causing or inducing a current in the present device sufficient for the device to radiate detectable electromagnetic radiation (preferably at a frequency that is an integer multiple or an integer divisor of an applied electromagnetic field), (b) detecting the detectable electromagnetic radiation, and optionally, (c) processing information conveyed by the detectable electromagnetic radiation. Generally, currents and voltages are induced in the present device sufficient for the device to radiate detectable electromagnetic radiation when the device is in a detection zone comprising an oscillating electromagnetic field. This oscillating electromagnetic field is produced or generated by conventional EAS and/or RFID equipment and/or systems. Thus, the present method of use may further comprise the step of (d) transporting or transmitting information from the present device (or sensor) back to a reading device, or (prior to step (a)) attaching or affixing the present device to an object or article (e.g., an identification card, packaging for goods to be shipped, etc.) to be detected, or otherwise including the present device in such an object, article or packaging therefor.

The present tags are designed at least in part to work with electronic identification and/or security systems that sense disturbances in radio frequency (RF) electromagnetic fields. Such electronic systems generally establish an electromagnetic field in a controlled area, defined by portals through which articles must pass in leaving the controlled premises (e.g., a retail store, library, etc.) or a space in which the article must be placed to be read and identified. A tag having a resonant circuit is attached to each such article, and the presence of the tag circuit in the controlled area is sensed by a receiving system that detects the tag and processes information obtained therefrom (e.g., determines unauthorized removal of an article or the identity of goods in a container labeled with the tag). Most of the tags that operate on these principles are single-use or disposable tags, and are therefore designed to be produced at low cost in very large volumes.

Alternatively, the present tag may take the form of a sensor, the RF signal modulation characteristics and/or properties of which may change as the characteristics and/or properties of the object or article to which it is attached change. For example, the present sensor may be attached to a stainless steel (or other metal) object, structure or surface. As the properties of the object, structure or surface change (e.g., the steel oxidizes, a metal having electromagnetic properties becomes magnetized or carries a minimum threshold electrical current, or the object or surface [regardless of its composition] changes temperature by a predetermined difference or a threshold amount), the characteristics and/or properties of the RF signal radiated, reflected or modulated by the present sensor also change in a detectable manner.

The present tags may be used (and, if desired and/or applicable, re-used) in any commercial EAS and/or RFID application and in essentially any frequency range for such applications. For example, the present tags may be used at the frequencies, and in the fields and/or ranges, described in the Table below:

TABLE 1 Exemplary applications. Preferred Range/Field Preferred Range/Field Frequencies Frequencies of Detection/Response of Detection/Response Exemplary Commercial Application(s) 100-150 KHz 125-134 KHz up to 10 feet up to 5 feet animal ID, car anti-theft systems, beer keg tracking 5-15 MHz 8.2 MHz, up to 10 feet up to 5 feet inventory tracking (e.g., libraries, 9.5 MHz, apparel, auto/motorcycle parts), 13.56 MHz building security/access 800-1000 MHz 868-928 MHz up to 30 feet up to 18 feet pallet and shipping container tracking, shipyard container tracking 2.4-2.5 GHz about 2.45 GHz up to 30 feet up to 20 feet auto toll tags

The present invention thus also pertains to article surveillance techniques wherein electromagnetic waves are transmitted into an area of the premises being protected at a fundamental frequency (e.g., 13.56 MHz), and the unauthorized presence of articles in the area is sensed by reception and detection of electromagnetic radiation emitted by the present device 100. This emitted electromagnetic radiation may comprise second harmonic or subsequent harmonic frequency waves reradiated from sensor-emitter elements, labels, or films comprising the present device that have been attached to or embedded in the articles, under circumstances in which the labels or films have not been deactivated or otherwise modified for authorized removal from the premises.

CONCLUSION/SUMMARY

Thus, the present invention provides a MOS identification device having an integrated interposer, and methods for its manufacture and use. The identification device generally comprises (a) an interposer; (b) an antenna and/or inductor on a first surface of the interposer; and (c) integrated circuitry on a second surface of the interposer opposite the first surface, the integrated circuitry having a lowest layer in physical contact with the second surface of the interposer. The method of manufacture generally comprises the steps of (1) forming the lowest layer of integrated circuitry on an interposer surface; (2) forming successive layers of the integrated circuitry on the lowest layer of integrated circuitry; and (3) attaching an electrically conductive functional layer to an opposite surface of the interposer. The method of use generally comprises the steps of (i) causing or inducing a current in the present device sufficient for the device to radiate detectable electromagnetic radiation; (ii) detecting the detectable electromagnetic radiation; and optionally, (iii) processing information conveyed by the detectable electromagnetic radiation and/or (iv) transporting or transmitting information from the present device (or sensor) back to a reading device. The present invention advantageously provides a low cost RF and/or RFID tag capable of standard applications and operations using conventional RF, RFID and/or EAS equipment and systems. By reducing the number of expensive and/or low throughput attachment steps, as well as reducing the cost of fabricating the active electronics, a low cost tag may be produced by directly printing or otherwise forming the circuitry on an interposer that is then relatively cheaply attached at relatively low accuracy to an inductor/carrier.

Novel elements of the invention may include (i) direct integration of circuit manufacturing/processing steps onto an interposer substrate and/or (ii) printing directly onto an interposer carrier, which is then inexpensively attached to an inductor formed on or from a low cost substrate material such as metal foil. In one embodiment, the inductor has a larger area (and thus may have two greater dimensions) than the interposer. Such direct manufacturing/processing steps are compatible with web, continuous, roll-to-roll and/or sheet processing and with conventional flexible, thin RF labels, and should provide an increased throughput in the tag manufacturing process. Fabrication of circuit elements directly on an interposer enables low cost manufacturing, as the resolution of the pick and place process for assembling the interposer and inductor/antenna is low. The inventive approach enables the efficient/low cost use of device substrate materials which are thermally and chemically compatible with RFID and/or EAS tag manufacturing and/or that provide appropriate barrier properties, but which otherwise might be too expensive if used for the interposer substrate of an entire tag.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

What is claimed is:
 1. An identification device, comprising: a) a recess-free interposer; b) a concentric and/or spiral antenna and/or inductor consisting of a single layer of conductive material attached or affixed to said interposer, said antenna and/or inductor having first and second opposed terminals; and c) integrated circuitry on a major surface of said interposer, said integrated circuitry being positioned over rings or loops of said antenna and/or inductor and electrically connected at a first location to said first terminal of said antenna and/or inductor and at a second location to said second terminal of said antenna and/or inductor, and said integrated circuitry comprising (i) a plurality of thin film transistors and (ii) conductive structures interconnecting the thin film transistors, the integrated circuitry comprising at least one printed thin film and having a lowest layer in physical contact with said major surface of said interposer, a first successive layer on said lowest layer, and a second successive layer on said first successive layer, wherein said lowest layer and said first and second successive layers taken together comprise an insulating thin film, a metal thin film, and a semiconductor thin film.
 2. The device of claim 1, wherein said metal thin film comprises a gate metal thin film.
 3. The device of claim 2, wherein said integrated circuitry further comprises a gate insulator layer between said gate metal thin film and said semiconductor thin film.
 4. The device of claim 2, wherein said integrated circuitry further comprises source and drain terminals.
 5. The device of claim 1, wherein said semiconductor thin film comprises said source and drain terminals.
 6. The device of claim 1, wherein said metal thin film comprises a plurality of metal conductors in electrical communication with said gate metal thin film and said source and drain terminals.
 7. The device of claim 6, wherein said integrated circuitry further comprises an interlayer dielectric between said metal conductors and said semiconductor thin film.
 8. The device of claim 1, wherein said at least one printed thin film comprises a gate metal thin film.
 9. The device of claim 1, wherein said at least one printed thin film comprises said dielectric thin film.
 10. The device of claim 1, wherein said at least one printed thin film comprises an interconnect metal thin film.
 11. The device of claim 1, wherein said interposer comprises a polyimide, a glass/polymer laminate, a high temperature polymer, or a metal foil.
 12. The device of claim 11, wherein said interposer comprises said metal foil, and said insulating thin film comprises a dielectric film on said metal foil.
 13. The device of claim 1, wherein said antenna and/or inductor comprises said antenna, and said conductive material consists of a metal.
 14. A method of reading an identification device, comprising: a) causing or inducing a current in the device of claim 1 sufficient for the device to radiate, reflect or modulate a detectable electromagnetic signal; and b) detecting said detectable electromagnetic signal.
 15. The method of claim 14, further comprising processing information conveyed by said detectable electromagnetic signal.
 16. The method of claim 14, further comprising attaching or affixing the device to or including the device in an item.
 17. The device of claim 1, wherein said interposer comprises a glass sheet, a glass/polymer laminate, or a high temperature polymer.
 18. The device of claim 17, wherein said interposer comprises said high temperature polymer.
 19. The device of claim 18, wherein said high temperature polymer comprises a polyimide, a polyethersulfone, a polyethylene naphthalate (PEN), or a polyether ketone (PEEK) sheet.
 20. The device of claim 18, wherein the high temperature polymer comprises a high temperature polymer sheet.
 21. The device of claim 18, wherein said interposer comprises a metal foil.
 22. The device of claim 21, wherein said metal foil comprises aluminum or stainless steel.
 23. The device of claim 21, wherein said metal foil comprises said stainless steel.
 24. The device of claim 21, wherein said interposer further comprises a dielectric and/or buffer layer on the metal foil.
 25. The device of claim 1, wherein said interposer comprises a flexible material.
 26. The device of claim 1, wherein said interposer has a thickness of from 25 μm to 200 μm.
 27. The device of claim 26, wherein said interposer has a thickness of from 50 μm to 100 μm.
 28. The device of claim 1, wherein said interposer has an area larger than 10 mm².
 29. The device of claim 1, wherein said integrated circuitry is on a first major surface of said interposer and said antenna and/or inductor is on a second major surface of said interposer opposite to said first surface.
 30. The device of claim 1, wherein said interposer has first and second pads thereon in electrical communication with said integrated circuitry, and said antenna and/or inductor has first and second terminals electrically connected to the first and second pads, respectively.
 31. The device of claim 30, wherein said integrated circuitry is on a first major surface of said interposer, said antenna and/or inductor is on a second major surface of said interposer opposite to said first major surface, and said first and second terminals are respectively connected to an exposed surface of the first and second pads at locations corresponding to vias in said interposer.
 32. The device of claim 1, wherein said first and second opposed terminals of said antenna communicate electrically through said metal thin film and said semiconductor thin film.
 33. The device of claim 1, wherein said semiconductor thin film comprises an inorganic semiconductor thin film.
 34. The device of claim 33, wherein integrated circuitry comprises CMOS transistors.
 35. The device of claim 1, wherein said integrated circuitry has an area substantially greater than an area of a conventional silicon RFID die or chip.
 36. The device of claim 1, wherein said integrated circuitry has a first area, said interposer has a second area, and said first area covers a majority of said second area.
 37. The device of claim 35, wherein said area of said conventional silicon RFID die or chip is about 0.01 cm².
 38. The device of claim 35, wherein said area of said integrated circuitry is substantially greater than about 0.01 cm². 